On 22/03/2024 18:19, Simon Peyton Jones wrote:
>From my understanding the biggest argument against this is the change in template-haskell?
Not specifically. My reservation is that
* it's an unforced change, * with no user demand * but some real user impact (you mention TH) * and some implementation cost (modest but very non-zero) * aiming to anticipate as-yet-unknown future requirements
That's not a combination I like. Pain now for possible (but uncertain) gain in the future.
I don't object to making types and terms behave similarly -- indeed I have invested lots of time working with Richard, Vlad, Andrei and others on proposals and MRs that move in this direction. I'm just very unconvinced about *this *proposal.
One minor point. In patterns we allow this: f ((,) @Int @[a] x y) = ... Here the type arguments are not type variables but full-blown types, and of course nested parens etc come "for free". But this proposal concerns data type declarations in which we definitely don't want fulll-blown types. So it's more than a "terms and types should be the same" discussion.
Simon
I see. I admit that I don’t feel expert enough to know if this design will turn out to be optimal. If forced to voice an opinion I am still slightly in favor of the proposal. Mainly because we have an implementor here who is motivated to implement this, thus the implementation cost seems less problematic. Best, Malte